Spectroscopic study of the high-spin states inPr135

An in-beam spectroscopic study of ${}_{}{}^{135}{}_{}{}^{}\mathrm{Pr}$ was made using a 91 MeV ${}_{}{}^{120}{}_{}{}^{}\mathrm{Sn}$ ${(}^{19}$F,4n) reaction. Two positive parity bands were observed based on the $g_{7/2}$ proton orbital with (π,α)=(+,±(1/2)). A strongly populated negative parity (-,-(1/2)) band was also seen (based on the $h_{11/2}$ proton orbital). The unfavored (-,+(1/2)) structure may also be present. In both the positive and negative parity bands the first backbend is attributed to the alignment of two $h_{11/2}$ protons on the basis of cranked shell model calculations. The crossing frequency was found to increase in the (-,-(1/2)) band because of blocking of the $h_{11/2}$ orbital. The alignment of protons in ${}_{}{}^{135}{}_{}{}^{}\mathrm{Pr}$ causes a shift of γ towards ∼+10° with nearly collective prolate deformation. Also, there is some evidence for a second backbend and an upbend in the case of positive and negative parity bands, respectively. They could result from the alignment of the $h_{11/2}$ neutrons.